One idea that would work well to even out the racial imbalances would be to reduce the health of dwarves by 2 while adding 2 to the health of elves. Level 18 health: Elf mages would have 19 hp, human mages 21 hp, and dwarf mages 23 hp. Elf priests would have 23 hp, human priests 25 hp, and dwarf priests 27 hp. Elf warriors would have 27 hp, human warriors 29 hp, and dwarf warriors 31 hp. This would take more away from the overwhelming favor for dwarves multiplayer has going for it as of now (and before).
I like the thought not sure if I would use those numbers. I would change mages to 17, 19 and 21 priests to 21, 24, 27 Warriors I would leave as is.